Researchers have found that happiness is not an isolated phenomenon, unique to an individual, but rather spreads through social networks. It seems almost obvious, especially when you hear phrases like "Laughing is contagious..."

The study also found that the closer a friend lives to a person, the stronger the effect. As distance increases, the effect decreases. This explains why friends who are next-door neighbors have an effect, but those who live around the block do not. Interestingly, the effects did not apply to co-workers and were stronger between same-sex than between opposite-sex pairs.

I had posted a topic earlier regarding smoking in networks. Clearly, social context affects health. Two previous studies, published in the New England Journal of Medicine, described the social network effects in obesity and smoking cessation.

So, it's not just colds and flu that get spread among friends - happiness does, too.

That is very interesting and it makes a lot of sense. If you are surrounded by others who are happy, their happiness is bound to affect you. It, however, would be interesting to see the correlation between the strength of your friendship and how the distance that you live affects the spread of happiness. For example, wouldn't a very close friend who lives far away affect your mood more than a next door neighbor acquaintance? How much of an effect would distance have?